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NAME="NET-COMMON-TCPIP-MANPAGES-BYTEORDER">byteorder</H1
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NAME="NET-COMMON-TCPIP-MANPAGES-BYTEORDER">byteorder</H1
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>BYTEORDER(3) System Library Functions Manual BYTEORDER(3)
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>BYTEORDER(3) System Library Functions Manual BYTEORDER(3)
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NAME
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NAME
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htonl, htons, ntohl, ntohs, htobe32, htobe16, betoh32, betoh16, htole32,
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htonl, htons, ntohl, ntohs, htobe32, htobe16, betoh32, betoh16, htole32,
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htole16, letoh32, letoh16, swap32, swap16 - convert values between dif-
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htole16, letoh32, letoh16, swap32, swap16 - convert values between dif-
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ferent byte orderings
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ferent byte orderings
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SYNOPSIS
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SYNOPSIS
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#include <sys/types.h>
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#include <sys/types.h>
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#include <machine/endian.h>
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#include <machine/endian.h>
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u_int32_t
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u_int32_t
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htonl(u_int32_t host32);
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htonl(u_int32_t host32);
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u_int16_t
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u_int16_t
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htons(u_int16_t host16);
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htons(u_int16_t host16);
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u_int32_t
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u_int32_t
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ntohl(u_int32_t net32);
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ntohl(u_int32_t net32);
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u_int16_t
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u_int16_t
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ntohs(u_int16_t net16);
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ntohs(u_int16_t net16);
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u_int32_t
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u_int32_t
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htobe32(u_int32_t host32);
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htobe32(u_int32_t host32);
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u_int16_t
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u_int16_t
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htobe16(u_int16_t host16);
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htobe16(u_int16_t host16);
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u_int32_t
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u_int32_t
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betoh32(u_int32_t big32);
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betoh32(u_int32_t big32);
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u_int16_t
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u_int16_t
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betoh16(u_int16_t big16);
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betoh16(u_int16_t big16);
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u_int32_t
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u_int32_t
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htole32(u_int32_t host32);
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htole32(u_int32_t host32);
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u_int16_t
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u_int16_t
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htole16(u_int16_t host16);
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htole16(u_int16_t host16);
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u_int32_t
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u_int32_t
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letoh32(u_int32_t little32);
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letoh32(u_int32_t little32);
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u_int16_t
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u_int16_t
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letoh16(u_int16_t little16);
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letoh16(u_int16_t little16);
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u_int32_t
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u_int32_t
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swap32(u_int32_t val32);
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swap32(u_int32_t val32);
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u_int16_t
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u_int16_t
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swap16(u_int16_t val16);
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swap16(u_int16_t val16);
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DESCRIPTION
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DESCRIPTION
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These routines convert 16- and 32-bit quantities between different byte
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These routines convert 16- and 32-bit quantities between different byte
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orderings. The ``swap'' functions reverse the byte ordering of the given
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orderings. The ``swap'' functions reverse the byte ordering of the given
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quantity, the others converts either from/to the native byte order used
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quantity, the others converts either from/to the native byte order used
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by the host to/from either little- or big-endian (a.k.a network) order.
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by the host to/from either little- or big-endian (a.k.a network) order.
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Apart from the swap functions, the names can be described by this form:
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Apart from the swap functions, the names can be described by this form:
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{src-order}to{dst-order}{size}. Both {src-order} and {dst-order} can
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{src-order}to{dst-order}{size}. Both {src-order} and {dst-order} can
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take the following forms:
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take the following forms:
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h Host order.
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h Host order.
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n Network order (big-endian).
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n Network order (big-endian).
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be Big-endian (most significant byte first).
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be Big-endian (most significant byte first).
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le Little-endian (least significant byte first).
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le Little-endian (least significant byte first).
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One of the specified orderings must be `h'. {size} will take these
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One of the specified orderings must be `h'. {size} will take these
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forms:
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forms:
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l Long (32-bit, used in conjunction with forms involving `n').
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l Long (32-bit, used in conjunction with forms involving `n').
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s Short (16-bit, used in conjunction with forms involving `n').
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s Short (16-bit, used in conjunction with forms involving `n').
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16
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16
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16-bit.
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16-bit.
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32
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32
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32-bit.
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32-bit.
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The swap functions are of the form: swap{size}.
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The swap functions are of the form: swap{size}.
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Names involving `n' convert quantities between network byte order and
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Names involving `n' convert quantities between network byte order and
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host byte order. The last letter (`s' or `l') is a mnemonic for the tra-
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host byte order. The last letter (`s' or `l') is a mnemonic for the tra-
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ditional names for such quantities, short and long, respectively. Today,
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ditional names for such quantities, short and long, respectively. Today,
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the C concept of short and long integers need not coincide with this tra-
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the C concept of short and long integers need not coincide with this tra-
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ditional misunderstanding. On machines which have a byte order which is
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ditional misunderstanding. On machines which have a byte order which is
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the same as the network order, routines are defined as null macros.
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the same as the network order, routines are defined as null macros.
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The functions involving either ``be'', ``le'', or ``swap'' use the num-
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The functions involving either ``be'', ``le'', or ``swap'' use the num-
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bers 16 and 32 for specifying the bitwidth of the quantities they operate
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bers 16 and 32 for specifying the bitwidth of the quantities they operate
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on. Currently all supported architectures are either big- or little-
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on. Currently all supported architectures are either big- or little-
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endian so either the ``be'' or ``le'' variants are implemented as null
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endian so either the ``be'' or ``le'' variants are implemented as null
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macros.
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macros.
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The routines mentioned above which have either {src-order} or {dst-order}
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The routines mentioned above which have either {src-order} or {dst-order}
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set to `n' are most often used in conjunction with Internet addresses and
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set to `n' are most often used in conjunction with Internet addresses and
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ports as returned by gethostbyname(3) and getservent(3).
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ports as returned by gethostbyname(3) and getservent(3).
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SEE ALSO
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SEE ALSO
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gethostbyname(3), getservent(3)
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gethostbyname(3), getservent(3)
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HISTORY
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HISTORY
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The byteorder functions appeared in 4.2BSD.
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The byteorder functions appeared in 4.2BSD.
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BUGS
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BUGS
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On the vax, alpha, i386, and so far mips, bytes are handled backwards
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On the vax, alpha, i386, and so far mips, bytes are handled backwards
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from most everyone else in the world. This is not expected to be fixed
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from most everyone else in the world. This is not expected to be fixed
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in the near future.
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in the near future.
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BSD June 4, 1993 BSD
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BSD June 4, 1993 BSD
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</PRE
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